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96 Blazer bogs down
My 96 blazer Boggs down when I hit the gas from a dead stop. It starts no problem and runs no problem while driving. The idle is choppy and fluctuates while it is sitting. I replaced the fuel pump and distributor. This problem only started after i replaced the catalytic converter. I also replaced the o2 and mass air flow. I removed the exhaust at the y and it still does it.
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93tracker5spd
Member Posts: 194
Hello! Of course without having the vehicle to run tests I can't speak dogmatically, but since you replaced the cat, the MAF, and the 02, we should be able to rule those out. That leaves the idle settings, the 96 had both a computer controlled idle, and mechanical settings. In this case, if you are the only owner, you would know if the mechanical settings had been changed, and that would leave only the electronic idle. If the vehicle had previous owners, I would proceed in this fashion. Have the computer re-learn the idle settings, (if the cat, MAF, and 02 were bad the fuel mix would be off), procedure below.
STEP ONE:
Disconnect the Negative cable for a few minutes. While The negative cable is disconnected, pump the brake pedal a few times to clear out any voltage in the system. Re-connect the negative cable after this is complete. Turn off air conditioning controls and all other accessories.
STEP TWO:
Run the engine up to operating temperature and shut off.
STEP THREE:
Apply the parking brake. Start the vehicle and place it in drive (A/T), or neutral (manual).
STEP FOUR:
Run the engine until the cooling fan has cycled on and off, or for a maximum of 10 minutes.
STEP FIVE:
Turn the ignition key off for at least 5 seconds.
STEP SIX:
Restart the engine and again shift into drive or neutral. Allow engine to run for at least 5 minutes.
STEP SEVEN:
Shut off engine for 10 seconds and restart.
STEP EIGHT:
That should do it. With engine stabilized and in closed loop, the IAC motor values should be between nine to 12 counts. If not, the adjustments may be tailored by adjusting the minimum air rate screw. More throttle valve opening equals lower IAC counts. Less throttle opening equals higher IAC counts.
If this fails to solve the problem, follow the testing procedure below to ensure that the IAC is in good working order. If all is well, try the mechanical adjustment described in step 8 above.
OPERATION
The engine idle speed is controlled by the ECM through the Idle Air Control (IAC) valve mounted on the throttle body. The ECM sends voltage pulses to the IAC motor causing the IAC motor shaft and pintle to move in or out a given distance (number of steps) for each pulse, (called counts).
This movement controls air flow around the throttle plate, which in turn, controls engine idle speed, either cold or hot. IAC valve pintle position counts can be seen using a scan tool. Zero counts corresponds to a fully closed passage, while 140 or more counts (depending on the application) corresponds to full flow.
TESTING
Disengage the IAC electrical connector.
Using an ohmmeter, measure the resistance between the IAC terminals. Make a note of the results.
Verify that the resistance between one set of IAC terminals is 20-80 ohms, and that the resistance between the other terminals is infinite. If not, the IAC may be faulty.
Also, with a small mirror, inspect IAC air inlet passage and pintle for debris. Clean as necessary, as this can cause IAC malfunction.
Good luck to you!5 -
Options93tracker5spd
Member Posts: 194
Hello again! Sorry for the delay in getting back, had computer system failure and decided it was time to upgrade. But back up and running now. Good to hear that the truck is running better, and thanks for posting updates. It's always good to know if a procedure works. Happy Holidays to you and yours and a great New Year!5
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Thanx